Do wooden arms warp

No, but my wooden leg does, causing me to often fall over on my way home from the tavern late on a winter's night. Or, at least that is what I told me captain......arg!

Tonywinsc, you are applying the "conservative" effect of denying reality .

Reed likes wood and many other companies believe in their materials. Is reed the only company that knows how to make an arm? I don't think so.

I am but lowly wetland scientist, not a material scientist, but after some initial skepticism, I am now quite convinced by both theoretical and empirical evidence that wood's "instability" need not automatically disqualify it from being used in a perfectionist analog set-up:
Theoretical- metal also is dimensionally unstable and has a coefficient of thermal expansion that can be quite a bit higher than certain kinds of wood. Same is true for some ceramics. Assuming that the wood is properly dried, we see the following coefficients (units are 10 minus 6th inches change per inch length per degree F), rounded to the nearest whole unit:
Aluminum 12
Brass 10
Copper 9
Steel 8-10
Stainless 6
Magnesium 14
Glass 5
Glass fiber/plastic 14
Porcelain 4
Titanium 5
Fir 2
Fir (cross grain) 17
Oak quarter sawn 30
Diamond 1
So if dimensional stability in terms of temperature change is the most important parameter, then diamond would be best. It's cheaper than unobtanium but it's a bitch to machine ;-)

The issue with respect to humidity is much more complex. My only comment is that I believe some wood tonearms are "stabilized" by impregnating the wood w resins or epoxies, not just by sealing the outside with a varnish or polyurethane finish.

Empirical- Others have noted that several of the finest tonearms wands are made of wood. We also see Lewm's report that his 2 wooden tonearms are dimensionally stable enough that over the course of 2 years, their alignment, when measured using the most precise (and most expensive) alignment jig currently available, has remained on the gnat's a$$ (my words not his). We also see that the physical properties of cartridges vary enough over time that in a highly resolving system, it is possible to hear changes in the sound with changes in VTA, VTF, and AS that are far less than anyone would previously have suspected.

As with most of these complex designs, esp. w transducers, it comes down to establishing design goals, optimizing the design to achieve those goals, and properly implementing the design. And then of course there is the subjectivity that the listener/user imparts to the process. So there will almost never be a single "best" material or "best" drive mechanism, or "best" stylus profile, or "best" circuit topology, etc., etc.

To get back to the OP's ?, the simple answer is that yes wooden tonearms can warp, but it appears that a properly designed, properly manufactured, and properly maintained tonearm wand can be made from wood, without warpage being a major constraint on its performance. However, I don't think I'd want to buy one if I lived in the Amazon ;-) Although now that I think about it, constant high temp and humidity is probably less harmful to alignment than the changing New England weather.

The question was 'Do wooden arms warp?' The answer seems
to be 'no problem at all'. The problem however seems to
be that we don't like simple answers while the philosophical
possibilties of the 'If... then' construction are endless.
Well I already own a cart with diamnod/stylus combo made
from one piece of diamond. What then can we expect 'if the
whole arm wand would be made from this material?'